#define _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS

#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#include<stdbool.h>
typedef char Datatype;
typedef struct stack {
	Datatype* a;
	int capacity;
	int top;
}ST;
void STInit(ST* ps);
void STDestroy(ST* ps);
void STPush(ST* ps, Datatype x);
void STPop(ST* ps);
Datatype STTop(ST* ps);

int STSize(ST* ps);
bool STEmpty(ST* ps);
void STInit(ST* ps)
{
	assert(ps);
	ps->capacity = 0;
	ps->top = 0;
	ps->a = NULL;
}

void STDestroy(ST* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->top = ps->capacity = 0;
}
void STPush(ST* ps, Datatype x)
{
	assert(ps);
	if (ps->top == ps->capacity)
	{
		int newcapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
		Datatype* tmp = (Datatype*)realloc(ps->a, sizeof(Datatype) * newcapacity);
		if (tmp == NULL)
		{
			perror("realloc failed");
			exit(-1);
		}
		ps->a = tmp;
		ps->capacity = newcapacity;
	}
	ps->a[ps->top] = x;
	ps->top++;
}

void STPop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);
	--ps->top;
}

Datatype STTop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);
	return ps->a[ps->top - 1];
}

int STSize(ST* ps)
{
	assert(ps);
	return ps->top;
}

bool STEmpty(ST* ps)
{
	assert(ps);
	return ps->top == 0;
}
bool isValid(char* s)
{
	ST st;
	STInit(&st);

	while (*s)
	{
		if (*s == '(' || *s == '[' || *s == '{')
		{
			STPush(&st, *s);

		}
		else
		{
			if (STEmpty(&st))
			{
				STDestroy(&st);
				return false;
			}
			char val = STTop(&st);
			STPop(&st);
			if ((*s == ')' && val != '(')
				|| (*s == ']' && val != '[')
				|| (*s == '}' && val != '{'))
			{
				STDestroy(&st);
				return false;
			}
		}
		s++;
	}
	bool ret = STEmpty(&st);
	STDestroy(&st);
	return ret;
}


